Geographic variation in meibomian oil levels

Abstract

Abstract: : Purpose: Meibometry allows quantitative analysis of meibomian oil levels on the eyelid margin. A previous pilot study using meibometry in 10 male volunteers suggested that meibomian lipid levels are higher at the temporal aspect of the lower lid. We performed a larger study to confirm that the casual (unstimulated) level of human meibomian oil varies at different positions along the lower eyelid margin and to investigate the relationship between upper and lower lid meibomian oil concentration. Methods: 44 volunteers participated in the study (27 male, 17 female; ages 18 – 29). None had evidence of meibomian gland dysfunction. Lid margin meibomian oil levels were measured using direct meibometry (Meibometer MB 550, Courage & Khazaka) at the temporal and nasal aspects of both lower eyelids and at the temporal aspect of the right upper lid. Results: The mean meibomian oil concentration at the temporal aspect of the lower eyelids was 3.75 mg/mm² (95% confidence interval(CI): 3.53–3.99mg/ mm² ), with a trend towards higher values in males 3.90mg/mm² (95% CI: 3.64–4.17 mg/mm² ), than in females 3.53 mg/mm² (95% CI: 3.10–3.96 mg/mm²), (P=0.10). The concentration of meibomian oil was higher on the right upper than the right lower lid by 1.10 (95% CI: 1.01–1.19). The meibomian oil levels were higher at the temporal than the nasal aspect of the lower lid by 1.17 (95% CI: 1.06–1.29). Subgroup analysis by sex showed trends towards these findings but only reached statistical significance (p <0.05) in the larger subgroup of male subjects. Conclusions: Meibomian oil levels vary across the lower lid margin and are higher temporally than nasally. Additionally, meibomian oil levels are higher on the temporal aspect of the upper lid than on the corresponding position on the lower lid. This may be the consequence of a greater number and larger size of meibomian glands in the upper lid.

Keywords: lipids • eyelid